arch/um/drivers/port_kern.c

   1 /*
   2  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include "linux/completion.h"
   7 #include "linux/interrupt.h"
   8 #include "linux/list.h"
   9 #include "linux/mutex.h"
  10 #include "linux/slab.h"
  11 #include "linux/workqueue.h"
  12 #include "asm/atomic.h"
  13 #include "init.h"
  14 #include "irq_kern.h"
  15 #include "os.h"
  16 #include "port.h"
  17
  18 struct port_list {
  19         struct list_head list;
  20         atomic_t wait_count;
  21         int has_connection;
  22         struct completion done;
  23         int port;
  24         int fd;
  25         spinlock_t lock;
  26         struct list_head pending;
  27         struct list_head connections;
  28 };
  29
  30 struct port_dev {
  31         struct port_list *port;
  32         int helper_pid;
  33         int telnetd_pid;
  34 };
  35
  36 struct connection {
  37         struct list_head list;
  38         int fd;
  39         int helper_pid;
  40         int socket[2];
  41         int telnetd_pid;
  42         struct port_list *port;
  43 };
  44
  45 static irqreturn_t pipe_interrupt(int irq, void *data)
  46 {
  47         struct connection *conn = data;
  48         int fd;
  49
  50         fd = os_rcv_fd(conn->socket[0], &conn->helper_pid);
  51         if (fd < 0) {
  52                 if (fd == -EAGAIN)
  53                         return IRQ_NONE;
  54
  55                 printk(KERN_ERR "pipe_interrupt : os_rcv_fd returned %d\n",
  56                        -fd);
  57                 os_close_file(conn->fd);
  58         }
  59
  60         list_del(&conn->list);
  61
  62         conn->fd = fd;
  63         list_add(&conn->list, &conn->port->connections);
  64
  65         complete(&conn->port->done);
  66         return IRQ_HANDLED;
  67 }
  68
  69 #define NO_WAITER_MSG \
  70     "****\n" \
  71     "There are currently no UML consoles waiting for port connections.\n" \
  72     "Either disconnect from one to make it available or activate some more\n" \
  73     "by enabling more consoles in the UML /etc/inittab.\n" \
  74     "****\n"
  75
  76 static int port_accept(struct port_list *port)
  77 {
  78         struct connection *conn;
  79         int fd, socket[2], pid;
  80
  81         fd = port_connection(port->fd, socket, &pid);
  82         if (fd < 0) {
  83                 if (fd != -EAGAIN)
  84                         printk(KERN_ERR "port_accept : port_connection "
  85                                "returned %d\n", -fd);
  86                 goto out;
  87         }
  88
  89         conn = kmalloc(sizeof(*conn), GFP_ATOMIC);
  90         if (conn == NULL) {
  91                 printk(KERN_ERR "port_accept : failed to allocate "
  92                        "connection\n");
  93                 goto out_close;
  94         }
  95         *conn = ((struct connection)
  96                 { .list         = LIST_HEAD_INIT(conn->list),
  97                   .fd           = fd,
  98                   .socket       = { socket[0], socket[1] },
  99                   .telnetd_pid  = pid,
 100                   .port         = port });
 101
 102         if (um_request_irq(TELNETD_IRQ, socket[0], IRQ_READ, pipe_interrupt,
 103                           IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM,
 104                           "telnetd", conn)) {
 105                 printk(KERN_ERR "port_accept : failed to get IRQ for "
 106                        "telnetd\n");
 107                 goto out_free;
 108         }
 109
 110         if (atomic_read(&port->wait_count) == 0) {
 111                 os_write_file(fd, NO_WAITER_MSG, sizeof(NO_WAITER_MSG));
 112                 printk(KERN_ERR "No one waiting for port\n");
 113         }
 114         list_add(&conn->list, &port->pending);
 115         return 1;
 116
 117  out_free:
 118         kfree(conn);
 119  out_close:
 120         os_close_file(fd);
 121         os_kill_process(pid, 1);
 122  out:
 123         return 0;
 124 }
 125
 126 static DEFINE_MUTEX(ports_mutex);
 127 static LIST_HEAD(ports);
 128
 129 static void port_work_proc(struct work_struct *unused)
 130 {
 131         struct port_list *port;
 132         struct list_head *ele;
 133         unsigned long flags;
 134
 135         local_irq_save(flags);
 136         list_for_each(ele, &ports) {
 137                 port = list_entry(ele, struct port_list, list);
 138                 if (!port->has_connection)
 139                         continue;
 140
 141                 reactivate_fd(port->fd, ACCEPT_IRQ);
 142                 while (port_accept(port))
 143                         ;
 144                 port->has_connection = 0;
 145         }
 146         local_irq_restore(flags);
 147 }
 148
 149 DECLARE_WORK(port_work, port_work_proc);
 150
 151 static irqreturn_t port_interrupt(int irq, void *data)
 152 {
 153         struct port_list *port = data;
 154
 155         port->has_connection = 1;
 156         schedule_work(&port_work);
 157         return IRQ_HANDLED;
 158 }
 159
 160 void *port_data(int port_num)
 161 {
 162         struct list_head *ele;
 163         struct port_list *port;
 164         struct port_dev *dev = NULL;
 165         int fd;
 166
 167         mutex_lock(&ports_mutex);
 168         list_for_each(ele, &ports) {
 169                 port = list_entry(ele, struct port_list, list);
 170                 if (port->port == port_num)
 171                         goto found;
 172         }
 173         port = kmalloc(sizeof(struct port_list), GFP_KERNEL);
 174         if (port == NULL) {
 175                 printk(KERN_ERR "Allocation of port list failed\n");
 176                 goto out;
 177         }
 178
 179         fd = port_listen_fd(port_num);
 180         if (fd < 0) {
 181                 printk(KERN_ERR "binding to port %d failed, errno = %d\n",
 182                        port_num, -fd);
 183                 goto out_free;
 184         }
 185
 186         if (um_request_irq(ACCEPT_IRQ, fd, IRQ_READ, port_interrupt,
 187                           IRQF_DISABLED | IRQF_SHARED | IRQF_SAMPLE_RANDOM,
 188                           "port", port)) {
 189                 printk(KERN_ERR "Failed to get IRQ for port %d\n", port_num);
 190                 goto out_close;
 191         }
 192
 193         *port = ((struct port_list)
 194                 { .list                 = LIST_HEAD_INIT(port->list),
 195                   .wait_count           = ATOMIC_INIT(0),
 196                   .has_connection       = 0,
 197                   .port                 = port_num,
 198                   .fd                   = fd,
 199                   .pending              = LIST_HEAD_INIT(port->pending),
 200                   .connections          = LIST_HEAD_INIT(port->connections) });
 201         spin_lock_init(&port->lock);
 202         init_completion(&port->done);
 203         list_add(&port->list, &ports);
 204
 205  found:
 206         dev = kmalloc(sizeof(struct port_dev), GFP_KERNEL);
 207         if (dev == NULL) {
 208                 printk(KERN_ERR "Allocation of port device entry failed\n");
 209                 goto out;
 210         }
 211
 212         *dev = ((struct port_dev) { .port               = port,
 213                                     .helper_pid         = -1,
 214                                     .telnetd_pid        = -1 });
 215         goto out;
 216
 217  out_close:
 218         os_close_file(fd);
 219  out_free:
 220         kfree(port);
 221  out:
 222         mutex_unlock(&ports_mutex);
 223         return dev;
 224 }
 225
 226 int port_wait(void *data)
 227 {
 228         struct port_dev *dev = data;
 229         struct connection *conn;
 230         struct port_list *port = dev->port;
 231         int fd;
 232
 233         atomic_inc(&port->wait_count);
 234         while (1) {
 235                 fd = -ERESTARTSYS;
 236                 if (wait_for_completion_interruptible(&port->done))
 237                         goto out;
 238
 239                 spin_lock(&port->lock);
 240
 241                 conn = list_entry(port->connections.next, struct connection,
 242                                   list);
 243                 list_del(&conn->list);
 244                 spin_unlock(&port->lock);
 245
 246                 os_shutdown_socket(conn->socket[0], 1, 1);
 247                 os_close_file(conn->socket[0]);
 248                 os_shutdown_socket(conn->socket[1], 1, 1);
 249                 os_close_file(conn->socket[1]);
 250
 251                 /* This is done here because freeing an IRQ can't be done
 252                  * within the IRQ handler.  So, pipe_interrupt always ups
 253                  * the semaphore regardless of whether it got a successful
 254                  * connection.  Then we loop here throwing out failed
 255                  * connections until a good one is found.
 256                  */
 257                 free_irq(TELNETD_IRQ, conn);
 258
 259                 if (conn->fd >= 0)
 260                         break;
 261                 os_close_file(conn->fd);
 262                 kfree(conn);
 263         }
 264
 265         fd = conn->fd;
 266         dev->helper_pid = conn->helper_pid;
 267         dev->telnetd_pid = conn->telnetd_pid;
 268         kfree(conn);
 269  out:
 270         atomic_dec(&port->wait_count);
 271         return fd;
 272 }
 273
 274 void port_remove_dev(void *d)
 275 {
 276         struct port_dev *dev = d;
 277
 278         if (dev->helper_pid != -1)
 279                 os_kill_process(dev->helper_pid, 0);
 280         if (dev->telnetd_pid != -1)
 281                 os_kill_process(dev->telnetd_pid, 1);
 282         dev->helper_pid = -1;
 283         dev->telnetd_pid = -1;
 284 }
 285
 286 void port_kern_free(void *d)
 287 {
 288         struct port_dev *dev = d;
 289
 290         port_remove_dev(dev);
 291         kfree(dev);
 292 }
 293
 294 static void free_port(void)
 295 {
 296         struct list_head *ele;
 297         struct port_list *port;
 298
 299         list_for_each(ele, &ports) {
 300                 port = list_entry(ele, struct port_list, list);
 301                 free_irq_by_fd(port->fd);
 302                 os_close_file(port->fd);
 303         }
 304 }
 305
 306 __uml_exitcall(free_port);